Fundamental to the well-being of an infant is the regulation of body temperature. In the new born, an infant weighing less than 5 kg., body temperature is regulated by the metabolism of small brown fat stores. The shiver mechanism, which is an important reflex in the adult, does not become significant until the infant is older.
The loss of body heat and decrease in body temperature can be devastating to an infant. Even with the smallest of temperature losses, in the range of 11/2.degree. C., oxygen demand will increae and the shift in metabolic pathways will create a severe metabolic acidosis. Continued decrease in temperature will eventually produce cardiac-respiratory arrest. Fortunately, adults do not usually have these problems.
Common techniques for maintaining temperature include infrared warmers, heating blankets, and warmed intravenous fluids. Adequate means are at hand to provide support for all of these needs with the exception of warming of intravenous (IV) fluids.
No practical fluid warming technique exists for patients weighing less than 10 kg. Devices currently in use have priming volume from between 40 to 70 ml. of fluid and due to their size, must be mounted some distance from the patient. There is therefore a temperature loss at slow intravenous fluid flow rates in the length of tubing interconnecting the warmer and patient. The total fluid weight of these patients is approximately 70% of their weight with circulating fluid volumes of 70 to 80 ml./kg. Thus, a 1 kg. neonate will have an approximate 700 cc total body water and a blood volume of 80 ml. (approximately the priming volume of most fluid warmers). Maintenance fluid requirements for most of these patients is in the range of approximately 4 cc./hr./kg.
The ideal fluid pediatric warmer will have a minimum volume with adequate warming at administration rates of 3 ml./hr. to 100 ml./hr., temperature controlled at 36.degree. C..+-.1.degree. C.
Prior art fluid warmers are only designed to take the chill off of cooled fluids, and do not achieve body temperatures for the fluid, or in the alternative, do so only for low fluid flow rates.